1. Field of the Invention
The present invention relates to engine testers, and more particularly, to internal combustion engine testers for measuring the friction power of engines, for viewing and optically measuring the velocity and displacement of internal engine parts, for measuring air flow rates, and for observing engine fluids.
2. Description of Related Art
It is often desirable for engine builders and technicians to operate an internal combustion engine throughout its normal speed range during testing. However, an operating engine creates extreme heat and noise. In the vicinity of an operating engine, hearing protection is required, there is a danger to technicians of being burned by hot engine parts, and ventilation of the exhaust fumes is necessary. In addition, testing an operating engine wears the parts by heating and cooling them. One solution to this problem has been to use a motoring dynamometer which is a dynamometer having a motor/generator capable of rotating the engine. Thus, the engine may be rotated without combustion occurring. Existing motoring dynamometers, however, lack the power to rotate a modern racing engine at high enough speeds to duplicate its normal range of operation. Furthermore, existing motoring dynamometers are prohibitively expensive for many shops.
Engine designers often need to know the power requirements of an engine and its individual parts. Existing motoring dynamometers are capable of measuring power requirements of an engine but are typically unable to rotate modern racing engines at speeds high enough to recreate their normal operating range.
It is desirable for engine builders and technicians to observe the inner workings of an engine when performing tests. In some cases, human eye observation can detect defects or inefficiencies in moving parts and fluids. In other cases, to detect inefficiencies, a non-contacting displacement follower which uses light to measure part displacement and velocity is required due to the high speed of the parts. Whether observation is done by instrument or with the human eye, illumination of the engine part is required. In general, windows have not been used on operating internal combustion engines for illumination because of the high operating temperatures and safety concerns. In one proposal, the performance of a cam shaft was optically measured by cutting away a portion of the valve cover. A motor was connected to the cam shaft to cause it to rotate. This method failed to recreate accurately actual engine operating conditions because the entire engine was not rotated at its normal operating speeds.
There is a need for engine builders to know the flow rate of air into and out of the cylinders of an engine. One proposed method of measuring engine air flow was to perform a bench test with a device known as a flow bench. The flow bench system was connected to an engine head which had been removed from an engine. An air pump was connected to the head to create a vacuum which simulated the vacuum created by the pistons in an operating engine. A flow meter was connected to the intake ports of the head to measure the air flow through the intake valves. Measurements were taken for numerous positions of the intake valves. The air flow was reversed and a similar set of flow readings was taken for the air passing through the exhaust valves. This apparatus and method was based on an artificially created air flow which failed to accurately reproduce the vacuum and exhaust pressures created by a set of moving pistons. Moreover, the flow readings were inaccurate since they were taken while the valves were stationary. Further, test results taken at different times could not be compared reliably due to failure to compensate for variables in weather conditions. In short, this apparatus and method failed to recreate the dynamic conditions of an operating engine.
It is desirable for engine builders to know the peak pressure r.p.m. value of a cylinder. That is, the number of revolutions per minute of the engine at which the pressure inside the cylinder reaches a peak. The output torque of an engine is maximized at this speed. An attempt was made to measure this value by removing the spark plug from one cylinder and connecting a pressure gauge to the cylinder in its place. This method failed because, for one reason, the pressure pulses from the firing cylinders affected the pressure measurements. Thus, there is a need for an effective method of testing peak pressure speed.
Another problem facing engine designers, which few if any have fully recognized, is the foaming of engine oil. Moving parts of an engine mix air into the oil. The greater the amount of air mixed into the oil, the less effective it is at lubrication. It is generally impractical, unsafe and ineffective to employ an observation window to view the amount of oil foaming in an operating engine. In the absence of an effective method of measuring engine oil foaming, there has been no effective solutions to this problem.